The compound 2-chloro-1,1,1,2,3,3,3-heptafluoropropane (CF3CClFCF3, CFC-217ba) is a useful intermediate for the preparation of hexafluoropropene (C3F6, HFP), a valuable fluoromonomer, and 1,1,1,2,3,3,3-heptafluoropropane (CF3CHFCF3, HFC-227ea), a fire extinguishant and propellant.
Commercial methods for the preparation of hexafluoropropene typically involve operating temperatures of greater than about 600° C. The high reaction temperatures lead to the formation of perfluoroisobutylene, an extremely toxic compound that is costly to remove and destroy (e.g., see European Patent Publication No. 002 098 B1). Processes for the manufacture of HFP at lower temperatures based on the use of acyclic three-carbon hydrocarbons or partially halogenated three-carbon hydrocarbons are disclosed in U.S. Pat. Nos. 5,043,491, 5,057,634 and 5,068,472.
U.S. Pat. No. 6,018,083 discloses a process for manufacture of HFP and HFC-227ea comprising (a) feeding CCl2═CClCF3, HF and Cl2 to a first reaction zone containing a catalyst comprising trivalent chromium and operating at a temperature of at least 250° C. but not more than 325° C. to produce a reactor effluent comprising C3Cl3F5, C3Cl2F6 and CFC-217ba, HCl and HF; (b) distilling the reactor effluent of (a) to produce (i) a low boiling stream comprising HCl, (ii) a reactant stream comprising an azeotrope of CFC-217ba and HF and (iii) a high boiling stream comprising C3Cl3F5 and C3Cl2F6; (c) reacting the CFC-217ba of reactant stream (ii) with hydrogen in the presence of a catalyst to produce a mixture comprising HFP and HFC-227ea; (d) feeding the C3Cl3F5 and C3Cl2F6 of high-boiling stream (iii) along with HF to a second reaction zone containing a catalyst comprising trivalent chromium and operating at a temperature of at least about 375° C. to produce a reaction product comprising CFC-217ba and HF; and (e) recycling the reaction product of (d) to the first reaction zone. U.S. Pat. No. 3,865,885 discloses the catalytic chlorofluorination of CH3CHFCH3 to CCl2═CClCF3; WO PCT 99/51555 discloses processes for the purification and use of CFC-217ba (e.g., dehalogenation of CFC-217ba to make HFP or hydodechlorination of CFC-217ba to make HFC-227ea) and azeotropes of CFC-217ba with HF; and U.S. Pat. No. 5,364,992 discloses the hydrogenolysis of halocarbons (e.g., CFC-217ba).
There remains a need for methods of manufacturing CFC-217ba.